Frozen ice confections comprising inclusions have hitherto generally been manufactured by an in-line process involving dosing the inclusions into the frozen composition using an inclusion feeder, blending the frozen composition and inclusions together to distribute the inclusions within the frozen composition and extruding and cutting the resulting product.
Similar methods for producing frozen confections comprising particulate edible material impressed onto the periphery of the body of a soft freezable confection, such as ice cream, are disclosed in U.S. Pat. No. 4,447,458.
A disadvantage of existing methods is the requirement to blend the individual components together to bring about dispersal of the inclusions with in the frozen composition. Conventionally, this is achieved by subjecting the combined materials to an active blending step, involving moving blending means such as a rotating paddle element. This blending step exposes the individual inclusions to significant shear effects, however, placing a significant restriction on the type of materials which can be incorporated into the frozen composition and consequently limiting the types of products which can be produced.
Where it is desired to produce an ice confection product comprising hard inclusions, such as nuts or chocolate pieces, for example, then the current, conventional method of manufacture can be used without difficulty. Such a method cannot generally suitably be used to prepare frozen ice confections incorporating dispersed inclusions of soft matter, such as soft fruit pieces, however, as the blending step has a detrimental effect on the integrity of the inclusion, giving an aesthetically unpleasing final product.
A further problem associated with conventional manufacturing techniques arises from the tendency of the inclusion to become dispersed to the outside edge of the mix during blending, as a result of the difference in viscosities of the components, leading to a lack of control over the pattern of distribution of the inclusions and hence to an unacceptably uneven distribution of inclusions in the final extruded product. Additionally, packing together the inclusions in an inclusion feeder prior to dosing leads to an increased risk of structural damage to the inclusion, rendering the method unsuitable for use in situations where retention of structural integrity of the inclusion is important (for example, with soft fruit pieces) and hence imposing limitations on the range of inclusion materials which can be used.
Where flows of two components are combined to give a mixed product, it is typically arranged that the individual flows converge approximately perpendicularly, in order to aid mixing. It is also known to blend flows of different materials to obtain dispersion of one material within the other by passive mixing by means of localised deflection of the combined flow in a static mixer. The incorporation of gelled inclusions in a frozen composition in such a manner is described, for example, in EP-A-0 811 324, Societe Des Produits Nestle S.A.).
The difficulties associated with processes for incorporating soft inclusions into frozen ice confections can be well illustrated by reference to the manufacture of ice cream products incorporating soft fruit inclusions. Such ice cream products are extremely popular with consumers and there is therefore considerable commercial interest in improved methods for their manufacture. Products incorporating discrete pieces of, or more especially whole, soft fruits, are particularly desired. Where the fruit ingredient is incorporated into the ice cream by the method described above, however, the shear effect to which the fruit is exposed upon introduction into the relatively higher viscosity ice cream flow, combined with the effect of the blending step tends to cause the fruit to break up, forming a pulp or puree, such that the final product contains very few, if any, distinct fruit pieces. Commercially available ice cream products comprising soft fruit inclusions notably tend not to have discrete whole fruits or even large pieces of fruit but rather have much smaller pieces. The larger the difference in viscosity between the ice cream and fruit components, the more this shear effect is exacerbated and so it would be expected to represent a particular problem where the ice cream used is higher viscosity ice cream prepared by extrusion at a temperature lower than is conventional in the art (such as is described in WO 97/39637 or WO 98/09534, both Unilever).
Approaches to overcoming the problems associated with incorporating soft fruit inclusions into ice confections which have been described in the literature include treating the fruit in some way before it is incorporated to make it less susceptible to shear damage. In U.S. Pat. No. 3,671,268 (Blake et al., assigned to Lever Brothers), for example, there is disclosed a method for preparing an ice cream product by forming a gelled fruit puree having a texture which is similar to the texture of fruit at room temperature and incorporating discrete pieces of this gelled puree into the ice cream.
Alternatively, soft fruit inclusions may be transformed into hard inclusions (for example by freezing and optionally dicing whole soft fruits) and incorporated into ice confections in the conventional manner. This is disadvantageous in economic terms as it involves increases in ingredient costs in addition to increased handling and processing costs.
Incorporation of fruit pieces into ice confections by careful hand mixing may be feasible on a small scale, say by an individual in the home, but is inappropriate for large scale industrial production. Even with hand mixing, it is difficult to produce a satisfactory product acceptable to the consumer in which the structure of the fruit pieces is not damaged. Controlling the distribution of fruit pieces in products prepared in this way also presents real problems.
Ice confections containing a plurality of inclusions prepared by automatically distributing the inclusions through a fruit feeder into the ice mix and disclosed in WO 98/37770.
There remains a continuing need to develop an improved method for incorporating inclusions, especially soft inclusions, into frozen ice confections which can be employed economically on a scale appropriate for industrial use. In particular, there remains a need to develop a method for incorporating fruit, especially soft fruit, inclusions into frozen ice confections wherein the structural integrity of the fruit inclusion is maintained to give an aesthetically pleasing product. A method which affords the possibility of controlling the pattern of distribution of the inclusions in the frozen ice confection product is particularly desired.